In the field of nanotechnology, much attention has been paid to the construction of nanometer- sized particles that can harbor drugs and other therapeutic agents. However, beyond the use of static ligands such as antibodies and small peptides, little work has been done on the specific targeting of the nanoparticles (NPs). This is an important component of NP design. By selectively delivering drugs to one cell over another, the efficacy of the drug can be drastically improved and consequently reduce the dosage needed and potential side effects. Viruses share many structural and physical similarities to an idealized NP. They are both about 100 nm in diameter, have hydrophilic shells and have long circulatory lives. However, viruses achieve a feat that few NP designs can;they efficiently target specific tissues and cells using virus envelope proteins (envs). The envs also do something that designed ligands may never achieve;they target specific cellular endocytic pathways, to access organelles such as the Golgi and the endoplasmic reticulum. Envs are also simple membrane fusion engines that sense the surrounding environment to trigger the release of their cargo in the cell cytoplasm at specific sites. In this proposal, we will optimize techniques to construct fluorescent NPs coated in the envs of Friend murine leukemia virus, Venezuelan equine encephalitis virus (NIH category B agent) and Ebola (NIH category An agent). Each env targets virus to unique cell receptors and endocytic entry pathways. We will investigate the cell and organelle targeting properties of the coated envs using state-of-the-art confocal microscopy and biochemical methods. Together with a novel way to target NPs, this work will allow a better understanding of the role of envs in infection and the entry pathways used by each virus. This will identify new targets for antiviral drug development. The NPs will also be useful in rapid virus diagnostic assays. Project Narrative: Highly purified virus membranes will be used to coat nanoparticles using a new method that preserves the useful features of the virus envelope proteins. The nanoparticles will then be tested for their ability to specifically interact with and enter cells. This will greatly aid in the development of targeted drug therapies and vaccine design.